How to count/show shader cycles or operations for shader profileing?

Well, I think the headline is self explanatory...

Is there any way to check how many cycles or math operations a specific shader is using?
If possible...
can you show the counts used on the current scene with its current conditions (fog, number of lights, etc)?

I've been struggling with this for 2 days without any success...

In the previous unity version (I'm using 2018.3.0f1 now) I was able to check some "math operations" once I selected the shader and clicked "compile and show code" on the inspector window. But with the current version, not any more :/

but, anyway, that was a mess...

So, I surprised to see that this is not a common topic when people is profileing, for instance, for mobile devices.

Any information will be more than welcome
thanks in advance!

 

Well, to be frank, it’s just not that useful for general profiling. Reducing ALU instructions won’t matter much if your memory bound, etc. It ends up being another counter, like “polygon count”, which is mostly meaningless in actual context. Also, all instructions are not created equal; some might take one cycle while another a dozen.

Better are profilers like the one in instruments, which can show you precisely how much time your shader is spending in each section of code, if it’s memory or ALU bound, etc.

 

Rely appreciate your quick answer jbooth but... I (kind of) disagree

Even if it's true that a simple "counter" per se is not that usefull, it gives an excellent insight (specially for low-end phones) of which are the performance limits (generally speaking) of each device under certain (full-screen-shader) conditions.

Besides, my problem (more specifically) is that I have no way to measure the difference of "perfomance consumption" (empirically speaking) between two shaders.

Specially if those are so "obscure" like the "standard shader" from unity with all their "variants" & branches

 

I think your asking for the wrong tool:

Lets say we have two shaders, one has an ALU instruction count of 54, another of 33. Which is faster?

You can't tell. The 33 one might be significantly slower than the 54 one, even if both are ALU bound and do no texture lookups.

So your basically asking for something to give you a bunch of information which won't tell you which is faster, and will most likely lead you to wrong conclusions.

One argument might be "Well, I want to see if I made the shader faster with my changes". But here too it can't tell you that. Because your code change might be less instructions, but the instructions your using might take longer to execute, even if they are again strictly ALU instructions and not something like moving some math to a LUT instead of computing it. And, on top of it, it's entirely platform dependent. An instruction which is fast on GCN might be slow on nvidia cards.

If your use case is to compare the performance of two shaders to see which one is faster, and for whatever reason you don't want to use a GPU profiler to do this (which will give you very detailed information), then write a test case that draws both shaders over the screen some crazy number fo times and run both and compare the speed.

People often want optimization to be simple "Keep it under this poly count", "Under this number of shader instructions", but if anyone tells you something like this, they are over simplifying the issue to the point where I question if they understand what they are doing.

 

hehehe... well, I think you overexagerated a bit with your last sentence but I understand what you mean.

No worries, GPU profilers are one of the tools of my arsenal too, but I was surprised that unity didin't include a tool that can give us (even if its only a brief and bit biased) overview of what's happening inside the shader.

 

You'll note that UE3 had this in their material editor, but removed it for UE4.

 

Do you think it will be vaild even for the "standard" with all their includes and pre-predefined variables?

 

BTW, it looks like, doesn't matter if I disable some of the platforms, it will always compile and show the same amount of variants.

 

Well, according to this... yes



Same amount of variants even if I reduce massively the number of platforms.

BTW, I'm using the Unity v 2018.3.0f1

 

@aleksandrk is the Mali offline shader compiler still relevant to testing URP shaders?
I get an error - 'binding' qualifier is not allowed in language version 300 es

Which other "easy to use" profiler do you recommend for testing the impact of various shaders created in Unity Shader Graph?

 

Thank you very much aleksandrk, it works now.